NuPS is a parameter server for machine learning with non-uniform parameter access.

This branch contains the version of NuPS that was used in the SIGMOD '22 paper on NuPS (author version). Details on the experiment settings of this paper can be found in docs/experiments-sigmod22.md. The latest version of NuPS can be found in the main branch of this repository.

The implementation of NuPS is based on PS-Lite and Lapse.

NuPS provides the following primitives:

• Pull(keys): retrieve the values of a set of parameters (identified by keys) from the corresponding servers
• Push(keys, updates): send updates for parameters to the corresponding servers
• Localize(keys): request local allocation of parameters
• handle = PrepareSample(N): prepare a group of N samples
• PullSample(handle): retrieve n samples from a prepared group

By default, primitives execute asynchronously. Wait() can be used to execute any primitive (except PrepareSample) synchronously. For example: Wait(Pull(keys)).

A simple example:

  std::vector<uint64_t> keys = {1, 3, 5};
  std::vector<float> updates = {1, 1, 1};
  std::vector<float> vals;
  ps::KVWorker<float> kv;

  kv.Wait(kv.Pull(keys, &vals));
  kv.Wait(kv.Push(keys, updates));

  kv.Wait(kv.Localize(keys));
  kv.Wait(kv.Pull(keys, &vals)); // access is now local
  
  auto h = kv.PrepareSample(3); // prepare a group of 20 samples
  kv.Wait(kv.PullSample(h, keys, vals)); // pull the 3 samples (keys.size() determines how many samples are pulled)

Build

NuPS requires a C++11 compiler such as g++ >= 4.8 and boost for some the application examples. On Ubuntu >= 13.10, you can install it by

sudo apt-get update && sudo apt-get install -y build-essential git libboost-all-dev

Then clone and build

git clone --branch sigmod22 https://github.com/alexrenz/NuPS/
cd NuPS && make

Getting started

A very simple example can be found in simple.cc. To run it, compile it:

make apps/simple

and run

python tracker/dmlc_local.py -s 1 build/apps/simple

to run with one node and default parameters or

python tracker/dmlc_local.py -s 3 build/apps/simple -v 5 -i 10 -k 14 -t 4

to run with 3 nodes and specific parameters. Run build/apps/simple --help to see available parameters.

Starting an application

There are multiple start scripts. At the moment, we mostly use the following ones:

• tracker/dmlc_local.py to run on a local machine
• tracker/dmlc_ssh.py to run on a cluster To see more information, run python tracker/dmlc_local.py --help, for example.

The -s flag specifies how many processes (i.e., nodes to use, e.g. -s 4 uses 4 nodes. In each process, NuPS starts one server thread and multiple worker threads.